The present invention relates to a conductor bar of an electric machine, and more particularly to a conductor bar which is surrounded by an insulating sleeve and which is impregnated with a hardenable impregnating medium.
Conductor bars for electric machines, as for example a squirrel cage motor, conventionally comprise a solid, usually rectangular, conductor surrounded by an insulating sleeve wound from a tape, for example a mica-containing tape. The so-wound bar is impregnated with a hardenable impregnating medium which is thereafter hardened. Such solid conductors have a smooth outer surface which the wound insulating sleeve closely follows. This arrangement can present difficulty with respect to the thorough impregnation of the insulating sleeve with insulating resins or varnishes since the insulating layers formed by the tape present a high flow resistance to the impregnating media perpendicularly to the surface of the layers. The penetration of the impregnating medium into the layered insulation takes place preferably parallel to the surface of the layers between them and in the space between the conductor surface and the insulating sleeve, i.e. in the lenghwise direction of the conductor. However, in conventional arrangements, imperfect impregnation of the insulating sleeve may result which degrades the operating behavior of the hardened insulation substantially.